Roll printer with decomposed raster scan and X-Y distortion correction

ABSTRACT

A photolithographic machine is described for transferring fine patterns from a photomask to a flexible roll-to-roll format. It is capable of printing multiple layers in exact registry onto a distorted format. It contains 1 to 1 reflective optics, dynamic distortion and magnification correction. The optical transfer assembly scans reciprocally across the format and back and the photomask/platen assembly moves incrementally forward between scans to complete a raster pattern. Both the object and image fields are autofocussed. The optical transfer assembly is retained into a straight-line scanning path by opposed air bearings retained on a straight guide. The photomask/platen assembly is retained into an orthogonal path by air/vacuum bearings operating on a vertical stone face. Together this arrangement substantially prevents yaw scanning errors. The web is fed through the machine from roll to roll without twisting. It remains stationary during each recording pass.

REFERENCE TO PRIOR APPLICATION

[0001] This application relies for priority on provisional applicationSer. No. 60/467,110 filed Apr. 30, 2003, and entitled “Roll printer withdecomposed raster scan and X-Y distortion correction”. A table ofadditional references, which are referred to in the specification,follows as Appendix 1.

FIELD OF THE INVENTION

[0002] This invention relates to the manufacture of semiconductorcircuits, display panels, photochemically produced parts and the like onflexible material, and more specifically to a roll-to-roll machine whichoptically copies an object field onto an image field at unitymagnification.

PRIOR ART

[0003] In semiconductor photolithography, in flat panel manufacture andin the manufacture of photochemically produced parts, the creation ofimages of very fine resolution and at the same time of very large areais of great importance. For example 1-2 micron image resolution is beingdemanded over fields or panel sizes as large as 24 inches, and 0.1micron resolution is required over fields as large as 25 mm. Such imagescontain from 2-500,000 resolved points across in one dimension, and arethus far out of reach of a stationary camera lens, however complex,which resolves—at a maximum—something like 50,000 points in eachdirection. The classical solution to this problem is to scan a smalloptical field of fine resolution across a larger format in some sort ofordered overlapping raster pattern. Images are transferred from a masterobject, usually a photomask, onto a format which is to become asemiconductor circuit, a display panel, a group of photochemicallyproduced parts, etc. Because the final format is much larger than theinstantaneous field of the optical system, the master and the format arescanned together in a raster pattern relative to the optical field ofthe transfer optics. This is done by introducing relative movementsbetween the master and format in one assembly and the optical imagetransfer system in another. Thus, for example an 18″×24″ format image at1-2 micron resolution can be produced by scanning a lens field 80 mm indiameter across the 18″, stepping downward and scanning backward,stepping down and scanning across, and repeating the raster scan untilthe entire area is covered. In order to be able to move the master imageand the format relative to the lens, and have the deposited image comeout in the correct orientation, the image must be erect, whereas asimple imaging lens produces an inverted image.

[0004] In semiconductor photolithography high resolution scanningoptical systems producing an erect 1:1 transfer of images have been usedfor many years. The image transfer has been made from master artwork,usually a glass or quartz photomask, onto a flat glass or siliconsubstrate—and more recently onto a flexible substrate, for examplephotoresist coated mylar or thin stainless steel. An early opticalsystem applied to this purpose was the Offner system (Ref. 2), used inthe Micralign projection aligners (Refs. 5, 6, 7, 10, 11, 12, 15). Thisoptical system comprised two mirrors, a large concave primary and aconvex secondary, the system working at a large decenter distance.Imagery at a 1:1 conjugate ratio is very good in a ring field of radiusequal to the system decenter. Along this arc the image is substantiallyaberration-free except for higher order astigmatism. These systems aredistinguished by having a well-resolved field which is shaped in anarrow arc centered around the system centerline. In conjunction withthe two spheres, Offner also used flat mirrors to erect the image. Asecond well-known 1:1 optical system used for photolithography is theWynne-Dyson system (Refs. 1, 9, 22, 23). These systems are alsodistinguished by having small, relatively high resolution fields anderect images (produced by a prism system).

[0005] In exposure applications similar to photolithography theadvantage of using mirror optics is clear. In order to take fulladvantage of available exposure sources, such as mercury or metal-halidearcs, the imaging optics must be able to function well over a broadrange of wavelengths. Achromatic systems (corrected for two wavelengths)are not sufficiently well corrected. Apochromatic systems (three or morewavelengths) are bulky and expensive. Mirror systems, however, arecorrected for all wavelengths, and hence insensitive to the color of thebroadband source.

[0006] A series of photolithographic instruments have been built using1:1 lens transfer optics (Refs. 14, 19, 26) in which the masterphotomask and the format are held rigid relative to each other and thatassembly is moved in a raster pattern through the object and imagefields of the stationary 1:1 lens optics, thus in successive stripescovering the entire field of the format. In this process the fields areoverlapped, from one successive scan to the next, and the field stop ischosen to be of a shape which causes the exposure in the overlappedregion to be even. This overlapping scan design was employed byFranklin, Ref. 4, using both a diamond and a curved field stop, by Jainusing hexagons, Refs. 14, 19, and by Whitney, Ref. 21, using a fieldstop whose side edges resemble a hexagon shape but which are adjustedinward or outward according to the measured illumination intensity asrequired to produce a very even field. The stationary optical transferassembly adopted in the designs of references 14, 19, and 26 used lensesbecause in the mechanical configuration which the inventor adopted therewas not room simultaneously to use a large primary mirror and to move alarge photomask and format. These and other designs where the optics areheld stationary have also been adapted to print on continuous rolls offlexible format material where the web is fed through the machine andadvanced frame by frame. In between panels the roll is advanced oneframe, each advance taking place after the mask and format assembly(carrying the part of the web between take-up rollers) has completed araster pattern to scan the master mask over the optical field of theoptical transfer assembly. However, because the optical transferassembly is held stationary and the mask and format assembly is moved intwo dimensions to complete a raster scan, the web is necessarilytwisted, to complete this series of motions.

[0007] Others have adapted the Wynne-Dyson optical design to a machinearrangement which raster scans a nearly vertical format at highresolution, holding the optical system stationary and moving thephotomask and format through its fields (Refs. 22, 23). A laser scannerhas been built by Tarnkin et al, Ref. 31, that uses an adaptation of theOffner design in which the primary mirror is split into two halves, butthe separate mirrors are not moved relative to each other to controlmagnification. Other similar machines were built by Dunn and others(Ref. 30) and by Kessler and others, (Ref. 32). All of these designs, asfar as is known, employ stationary transfer optics.

[0008] It is inherently more difficult mechanically to introduce twoorthogonal motions into a single moving assembly than it is to split thetwo motions, introducing the cross-scan by the motion of one assemblyand the intermittent motion, between scans, into the orthogonal member.If the motion components are split each is a straight line movement andthe expense associated with X-Y stage motion is avoided. The drives aresimplified and mechanical errors associated with X-Y stage droop areavoided.

[0009] Display panels and semiconductor wafers change their dimensionsduring processing. Flexible plastic substrates are much moredimensionally unstable, in that they are sensitive to humidity as wellas to heat and process variables. Photolithography of display panels andsemiconductor circuitry requires that many layers be laid down in exactregistry with one another, the registration requirement from layer tolayer being considerably smaller than the amount of distortion expectedto be encountered in the substrate or web material. Thus it has beenrecognized that, when flexible substrates are used, the effects ofdistortion, usually of unpredictable amounts and in unpredictabledirections, must be overcome if precise overlay registrationrequirements are to be met. To counter these effects several groups haveintroduced a slight relative motion into the photomask/format assemblyand/or a slight magnification change into the transfer optics before orduring the scanning process. Jain (Ref. 19) introduced a technique ofperiodically realigning the photomask and the format. Whitney (Ref. 21)introduced a relative motion of the mask relative to the format duringthe course of the scan pass to counter distortion during each singlepass in a large proximity printer. Sheets et al introduced amagnification change stage comprising a very weak telephoto telescopewith adjustable distances between the lenses (Ref. 23) to counterscan-to-scan distortion. This adjustment was made prior to the start ofscanning and was not dynamic nor automatic. Jain et al (Ref. 26) andAllen et al (Ref.28 and 29) both introduced schemes for changingmagnification during scanning by changing lens or prism elementseparations. Both systems involved stationary lens optical transferassemblies.

[0010] The requirement for mass production of display panels on flexiblematerial makes overlay accuracy from layer to layer a necessaryrequirement. Thus the ability to introduce both Dynamic DistortionControl and slightly variable magnification during the course ofcompleting the raster scanning pattern is a necessary feature.

[0011] Another characteristic of erect image optical transfer assemblieswhere the photomask and the format are co-planar (cf. Ref. 19) is theirerror sensitivity to a relative rotation in yaw (around an axis mutuallyperpendicular to the line connecting the centers of the optical fieldsand to the photomask plane). If this geometry is used, it is verynecessary that this sensitivity be eliminated or reduced to a very smallvalue.

[0012] When a large photomask and a large web are laid side by side andincorporated mechanically into a single assembly, and if that assemblyis moved back and forth and intermittently forward across the fields ofa stationary optical system to produce the raster scanning pattern, thenthis scanning pattern requires that the web be twisted in ways whichwill tend to introduce a component of unwanted distortion. It isdesirable that the machine arrangement be such that the web is fedstraight through from one reel to the other without any twisting.

[0013] Multiple processes may be sequenced within the same physicalmachine, e.g. a first pattern which comprises a writing stage, treatedin detail in the description which follows, may be followed by adevelopment stage, a laser annealing stage, etc. It may be followed byprovision to record another complementary pattern on the back of thesame web substrate, with a requirement for equal precision in thelocation and resolution of the pattern. Transport of the web throughthese subsequent stages should be carried out without twisting the web,if distortion is to be minimized.

SUMMARY OF THE INVENTION

[0014] This invention is a new design of a precision one-to-one transferprinting machine which prints high resolution images of 18″×24″ or morefrom a rigid photomask to a flexible roll-to-roll web format. The longdimension is not limited to 24″ in this design but may be any length,like 40″ or 48″ if desired. The 18″ dimension may be increased byscaling the assembly.

[0015] The invention comprises a new machine layout, including anoptical transfer assembly which shuttles reciprocally with respect to anintermittently stationary photomask and format assembly to provide incombination a raster scan, also providing slightly adjustablemagnification, a reciprocally moving illumination system, and aphotomask articulated within its frame to introduce slight relativemotions in two dimensions. This combination of elements involving themoving optical system and the intermittently stationary photomask andformat solves the notable problems of previous designs in a simplemanner. There is plenty of room to use a large reflective achromaticoptical system and still scan a large format, the two-dimensionaleffects of distortion are removed, the introduction of yaw angle erroris avoided, and the web is fed through the machine without twisting orstress. It is designed to produces high-resolution images (better than 2micron least dimension) everywhere on the format and better than 1micron layer to layer overlay accuracy. The optics are completelyachromatic and the system is therefore insensitive to the wavelengthcomposition of the light which is supplied by the illuminator.

[0016] The photomask and the vacuum platen are coplanar facing downwardand during exposure vacuum holds a portion of the web tightly to theplaten. The photomask and platen comprise a single assembly which movesforward incrementally during exposure, and which remains stationaryduring the time that the optical transfer assembly shuttles reciprocallyacross or back beneath them. After each optics scan pass is completed,in either the plus or minus X direction, the photomask/platen assemblymoves forward the width of one scan pass, again remaining stationarywhile the return optics pass is completed. The combination of these twomovements, the reciprocating movement of the optical transfer assemblyand the intermittent movement of the photomask/platen assembly, togethercomprise a raster scan covering the entire 18″ width and 24″ length (orlonger) of the image format.

[0017] Both the optical transfer assembly and the photomask/platenassembly are supported on air/vacuum bearings and ride on stone planes,one motion orthogonal to the other. The photomask/platen assembly hasside guide bearings of the air/vacuum type, riding on a vertical stoneface. The optical transfer assembly is retained into a straight-linemotion by two sets of opposed air bearings guiding on opposite sides ofa smooth vertical plate.

[0018] The precision with which orthogonality of the transferred patternis maintained is taken from an initial orthogonal adjustment of thevertical edge of the top portion of the stone base structure guiding thephotomask/platen assembly, with the vertical plate guiding the opticaltransfer assembly cross-motion.

[0019] Autofocus is maintained by two proximity sensor gages and twoservoed lifters, one under the object field and one under the imagefield. Optionally the photomask is carried in a vacuum support framethat helps to maintain the image surface flat, countering sag due togravity. However, since focus is performed independently on each field,and corrected independently on each field, the object end of theapparatus can ride over a considerable residual curvature in thephotomask without image degradation or change in magnification. For asimilar reason, the image end of the optical train can also tolerateconsiderable variation in the level of the format plane.

[0020] The web is carried straight through the machine, from roll toroll, without twisting. A portion of the web is held firmly against thevacuum platen as it is exposed during a frame. It is advanced one swathwidth (˜80 mm. allowing for slight overlap) between scans, carriedintermittently forward with the photomask/platen assembly, until theentire raster scan is complete. The vacuum then releases, the webadvances a complete frame on the roll-to-roll drive, the platen returnsto its starting position, and the vacuum platen seizes the next sectionof the web for the start of the next frame.

[0021] The emergent end of the fiber bundle carrying the illuminatorlight is reciprocally scanned, in synchronism with the optical transfersystem movement during a panel exposure.

[0022] When a second or subsequent layer is being exposed, in registrywith the first, before the first raster scan of the second exposure, theoptical transfer assembly makes a single pass across the format, withthe actinic exposure light occluded. At the start and end of this passthe positions of fiducials located on both the near and far top cornersof the existing format image are measured relative to correspondingphotomask fiducials, together with the positions of two next fiducialsalong the near and far sides of the first layer format image, againmeasured relative to corresponding fiducials on the photomask. Thedifferences between corresponding readings and their predicted positions(which are errors or distortions in the existing format image) are usedby the control computer to compute both the Dynamic DistortionCorrection component of the photomask relative motion and the slightmagnification adjustment which is applied to the optical transferassembly from pass to pass during the exposure scan.

[0023] The optical transfer assembly is constructed so that first andthird spherical mirrors comprise two symmetrical optical elements, sideby side and arranged to be nominally concentric with each other. Uponcommand, they move up to ±20 microns backward and forward relative toeach other along the axis of the system, supported on flex joints,supplying a change in system magnification up to at least 1×10⁻³, as maybe required for distortion compensation.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] A better understanding of the invention may be had by referenceto the following description taken in conjunction with the followingdrawings in which:

[0025]FIG. 1 is an oblique view of the optical transfer optics;

[0026]FIG. 2 is a top view of the optical transfer assembly and guidebearing subassembly;

[0027]FIG. 3 is a front view of the optical transfer assembly and guidebearing subassembly;

[0028]FIG. 4 is a side view of the optical transfer assembly showing itin relationship to the photomask/format fields of view, the stone basestructure, the air bearing supports and opposed air guide bearings;

[0029]FIG. 5 is a rear view of the optical transfer assembly, thesupport bearings and the guide bearing subassembly;

[0030]FIG. 6 is a diagram of the optical resolution over the 80 mm.field showing the arc of good focus;

[0031]FIG. 7 is a field stop which admits only the object points lyingwithin the arc of good focus, FIG. 6;

[0032]FIG. 8 is a modulation transfer function of the optical system;

[0033]FIG. 9 is a point spread function of the optical system;

[0034]FIG. 10 is a graph of the system response to 2 micron lines andspaces;

[0035]FIG. 11 is a diagram of the raster scanning pattern shown as thecomposition of the motions of two assemblies;

[0036]FIG. 12 is a schematic diagram of the photomask/vacuum platenassembly; in combination with the optical transfer assembly and theillumination assembly.

[0037]FIG. 13 is a schematic drawing of the roll-to-roll feed inrelationship to the vacuum platen;

[0038]FIG. 14 is a functional block diagram of the System Controller andthe Drive and Actuator functions.

[0039]FIG. 15 is a schematic drawing of the illumination system.

[0040]FIG. 16 is schematic drawing of the photomask subassembly and itsfiducial references, in relationship to an existing format image and itsfiducials on the web.

[0041]FIG. 17 is an illustration of a succession of astigmatic imagesobtained from an astigmatic gage moving through the position of goodfocus;

[0042]FIG. 18 illustrates a typical voltage response from an astigmaticgage as a function of focal distance;

[0043]FIG. 19 is a schematic drawing of the photomask subassemblyshowing the position of the alignment actuators.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0044] The preferred embodiment of this invention is an optical machinefor the processing of display screens, multilayer circuits constructedon flexible material and the like. It comprises a series of assemblieswhich operate together under the control of a multiaxis controller, toproduce large exposed patterns or panels in a semi-automatic manner. Theseparate assemblies will be described separately followed by adescription of the way in which they work together.

[0045] The optical transfer assembly 1, FIGS. 1-5, which images detailfrom the photomask 2 to the format 3 is an all-reflecting erectingconfiguration similar to the arrangement first described by Offner, Ref.2 except that the primary concave mirror is composed of two controllablymoveable smaller mirrors, the secondary mirror is aspheric, and theerecting mirrors are differently and more advantageously arranged. Thetwo primary mirrors are concave spheres 4, 5 and one, the convexsecondary, is aspheric, 6. FIG. 1 shows an oblique view of the opticalarrangement of the optical transfer assembly, as seen from above. Thesame assembly is shown in top view, front view, side view and rear viewin FIG. 2-5, together with the surrounding air/vacuum support bearings26, 27, 28, opposed air guide bearings, 30, 31 and bearing guide 32,mounted on the stone base structure 29.

[0046] The design, as used here, is optimized to provide a resolution ofabout 1.5μ over an arc shaped object field 21 and image field 81, whichis 80 mm high by approximately 3 mm wide, FIG. 2. The centers of thefields, 7, 8, are located approximately 19.5″ apart and a well-correctedarc field of object points is projected down from the photomask at 7 andup onto the format located at 8. The quality of spot imagery within thisarc is shown as the highly resolved arc of image points in FIG. 6.Within the arc shaped field stop 21, FIG. 7, this optical system hassubstantially diffraction limited imagery, as shown by the modulationtransfer function for the central points, FIG. 8, and the point spreadfunction, FIG. 9. It has the ability to completely resolve 2 micronlines and spaces, as is graphically illustrated in FIG. 10. The arctuatefield stop 21, FIG. 7, is 80 mm. high by 3 mm. wide. It is tapered oneach end, and on each pass of the optical transfer assembly across theformat the scanned field overlaps the previous field by one half of thetapered section. Thus exposure is smoothed out between scans and bandingis avoided

[0047] Two versions of the optical system are presented. The simplestcomprises a concave sphere 4, a convex sphere 9, and a concave sphere 5in series (plus erecting mirrors). The sphere centers and curvatures arearranged in a form resembling the configuration originally described byOffner, but the primary mirror of this system is made up of two parts,4, 5, which are slightly movable axially, with respect to each other.The optical constants of a typical all spherical example of this systemare described completely in Table 1. In the second, preferred,embodiment, an example of which is described in Table 2, the centralconvex mirror at the system pupil is replaced by an aspheric mirror 6.This latter system is slightly faster. It is arranged to be considerablyfurther off-axis, covers a much wider scanning field of view, and hasits fields rotated 90 degrees for optimal mechanical scanning of thephotomask and format. (see the scanning pattern, FIG. 11). This lattersystem (FIG. 1-5) takes a complex of six flat mirrors, three on theobject side, 10, 11, 12, and three on the image side, 13, 14, 15, torotate the field 90 degrees and erect the image at the same time. Thesystem operates at about f/4.05 in the meridian along the scanningdirection, about f/4.85 in the meridian along the arctuate field.

[0048] Offner described a system of four plane erecting mirrors. Hismirrors, however, bend inward (see also Ref. 31 for another suchsystem), decreasing the distance between field centers. The erectingmirror system 10-15, and the increased decenter employed in the asphericdesign presented in this patent specification (Table 2) brings thefields outward so that their centers are separated by more than thewidth of the web, while the field is simultaneously rotated to cover themaximum web area per pass. In the aspheric system the optics are 122 mm.off center and, because of the additional offset caused by optimalpositioning of the mirrors, the distance between the object and imagefield centerlines is 19.3 inches.

[0049] Because the fields 7, 8 are 19.3 inches apart in thereciprocal-scan direction, the width of the web that can be covered isat least 18″, and because the arctuate field 21 is 80 mm. from top tobottom, slightly more than a 24″ format can be covered in eightreciprocal raster passes.

[0050] The two concave primary mirrors 4, 5 are used because the systemis required to change magnification by up to one part in 10³ tocompensate for possible Y direction format distortion. These twoelements are flex mounted and provided with a piezo or micro-stepperdrive 16 (FIG. 12) so that they may be driven reciprocally axially up to±2082 , one forward, the other back. This reciprocal motion produces thenecessary magnification change without any significant imagedegradation. When one mirror is moved inward and the other outward, oneconjugate of the system shortens, the other lengthens by the same amountand the magnification changes by the ratio of conjugate distances. Smallspherical mirrors are among the least expensive precision opticalelements. Thus the two smaller primaries are less expensive and, ofcourse, lighter than a single larger mirror.

[0051] The imaging optical system of concave and convex mirrors 4, 5, 6is made as one subassembly mounted and adjusted together, and the sixerecting mirrors 10-15 comprise a second subassembly. Thus the mirrorswith optical power are mounted (and tested) together, the erectingmirrors are mounted together and checked for orthogonality, and the twosubassemblies are then fixed with respect to each other.

[0052] To facilitate calibration of the autofocus and initial focusing,the last flat mirrors, 10, 15 on both the object and image sides aremade as dichroics, permitting one to look through them, and to view theobject or image surface through the mirror plane in other than actiniclight.

[0053] The preferred illuminator arrangement is shown in FIG. 15. Theillumination source 17 is typically an arc source, as for example theUshio SMH UVI 200 watt Emarc lamp and elliptical reflector system, madeby Ushio America of Irvine, Calif., or another lamp/reflector assemblyof the same series up to 600 watts. These are all mercury enhanced metalhalide lamps mounted in an elliptical reflector. Their reflected energyis concentrated into a spot in front of the reflector with an angularityof f/1. Each has an average lifetime of 1500 hours. Another lamp andreflector system that can be used is the long life Hamamatsu 575 wattmetal-halide lamp L5431 and reflector system, which has an averagelifetime of 3000 hours.

[0054] An integrator rod 18 (FIG. 15) is placed so that its entranceface is located at the front spot focus, collecting a good portion ofthe light. The integrator rod is a solid-state light tunnel, typically abar of fused quartz of rectangular cross-section with all six of itssides polished. Such rods are supplied by Ariel Optics, Inc. of Ontario,N.Y. The function of the rod is to take a cone of irregularlydistributed light in at one end, totally internally reflect each rayseveral times off the four longer sides and put out a cone of light atthe other end which is evened out spatially over the emergent face. Thesides of the rod are all parallel to each other, and consequently, thereflections which a ray undergoes passing through the rod all occur atequal angles. There is no growth or shrinkage in the f/# of the lightbeam in its passage through the rod. If a beam goes in at f/1 it willemerge at f/1. However, a beam that went in with a hot spot in thecenter or some other uneven distribution will be radially invertedseveral times and will emerge quite evenly distributed.

[0055] The radiation cone emergent from the integrating rod 18 will beat f/1, and the transfer optics accept f/3.5. Therefore the f/1 conemust be transformed into an f/3.5 cone by reimaging, using a transferlens 19 having conjugate distances in the ratio of 1/3.5. The entranceend of the fiber bundle 20 is placed at the image of the emergent faceof the integrator rod, formed by the transfer lens. A properly chosenfiber bundle has no trouble accepting and passing f/3.5 light, which isrequired in the example system.

[0056] The cross-sectional aspect of the fiber bundle 20 is circular atthe source end, emerging in an arc shape 23 matching the arctuate field21 (FIG. 7) at the photomask end. The fiber arrangement within the fiberbundle is randomized, further contributing to the even distribution oflight over the field. The lamp and reflector, the integrator rod, thetransfer lens and the entrant face of the fiber bundle are stationary.Intermediate between the entrance to the fiber bundle and the exit thereis a loop of fiber arranged to flex easily and to reach across theformat. The emergent portion of the fiber bundle is fixed in an assembly24 that is driven in conjunction with the optical transfer assembly 1through the cross-scan portion of the raster pattern. Precision is notimportant in this drive, and there is no yaw angle sensitivity.

[0057] A fiber bundle is not 100% efficient, since it is comprised ofindividual clad fibers whose cross-sections are circular. The claddingtakes up some room and there are voids between the fibers. Overall, thepacking efficiency of such a well-made fiber bundle is about 80%. It hasan additional slight attenuation due to absorption of the quartz, and ofcourse accepts energy only up to the numerical aperture for which it isconstructed.

[0058] An alternate arrangement for the illuminator, delivering slightlymore exposure energy, comprises a doped mercury line source andreflector subassembly, focused onto a similar incoherent quartz fiberbundle. Such a source and reflector emits well above 100 watts/inch ofuseable exposure energy and slightly more hot plasma is exposed to theoptical collecting system. A source of this type, with its power supply,can be procured from Accurate Arc of Van Nuys, Calif.

[0059] Either type of source discussed above is adjustable in intensityby as much as 50%, by changing the power supply input voltages. Thusexposure is held constant as the lamp ages, or exposure can be adjustedto suit the chosen throughput speed. Fan cooling is required for eithersystem.

[0060] In either system, a reflecting shutter 22 is provided, swinginginto the beam just before the exterior focus of the arc, and just beforethe radiation enters the integrating rod or fiber bundle. This shutterprovides a means of shunting radiation to the side when the system is inan idle mode.

[0061] Because the imaging optics are entirely reflective, the system iswavelength insensitive, and many other light sources may be considered.Among these are excimer lasers, RF Fusion sources and high pressuremercury arc lamps. The operating source and wavelength are selected tofurnish actinic radiation suitable to satisfy the requirements ofdifferent combinations of sensitive material and exposure conditions atthe format.

[0062] The optical transfer assembly 1 (FIG. 1-5) is carried on threeair/vacuum aerostatic bearings 26, 27, 28 riding on the smooth surfaceof a horizontal stone base plate 29. Two of the support bearings arelocated one 26 directly under the object plane 7 and one 27 directlyunder the image plane 8. The third support bearing 28, is located at therear of the optical assembly, underneath a point mid-way between the twosections of the primary mirror, forming a triangular support with thefirst two.

[0063] The bearings are preferably of types made by Dover InstrumentCompany of Massachusetts or by New Way Machine Components, Inc of AstonPa. Such air/vacuum bearings have a flying height of perhaps 3-5microns, a distance which is held quite constant by the balance betweenthe pressure of the air flowing out from an outside ring (or a porousbottom surface) and the restoration force of vacuum drawn on an innerring. The two forces balance, maintaining the bearing and the weightthat it is supporting at a constant height. The bearings are“aerostatic” which means that they float at their adjusted height evenwhen they are not moving sideways. They will maintain their correctheight during the optical transfer assembly turnaround and, because oftheir stiffness, there will be almost no interval of adjustment andrecovery. Typically the compliance of air/vacuum bearings in compressionis between 2.5 and 5×10⁵ lbs/inch of deflection, and the typical vacuumpreload of the air/vacuum type bearings is 25 inches of mercury. Eachbearing consumes less than 2 cubic feet/hour of clean dry air, suppliedat 60-80 lbs/in².

[0064] The reciprocal motion of the optical transfer assembly isretained in a very precise straight line by the restraining force of twosets of opposed aerostatic air bearings 30, 31, referencing on eitherside of a smooth vertical guide plate, 32, which is attached to aninternal vertical wall of the stone base structure 29, FIG. 2 and 3.These bearings each have a stiffness in compression of about 2.5×10⁵lbs/inch of deflection at 5 microns of flying height, and any attempt ofthe optical transfer assembly cross-motion to depart from astraight-line path is met by immediate resistance of a large andincreasing restoring force. Opposed air bearings are obtained from thesame sources as are the air/vacuum type bearings. Because of theopposing forces, they also float when the assembly is at rest.

[0065] The lower part of the stone base structure 29 (FIG. 2-5), is flatand extends about 45 inches in the cross-scan direction, about 20inches, back to front. An internal face is also finished perpendicular,and serves as a reference mounting face for the flat smooth guide plate32 guiding the two sets of opposed air bearings 30, 31.

[0066] The upper portion of the stone base structure 33 serves as asupport for the photomask/platen assembly 39. Its side perpendicularface 34 is finished flat and serves as a reference face for thephotomask/platen assembly side-guide air/vacuum bearings 35, 36. Becauseof their vacuum preload they cling very well to a smooth vertical face,and operate at a constant standoff distance from that surface.

[0067] The optical transfer drive assembly 37, (FIG. 12), is preferablya cable or band drive. It is arranged to pull the optical transferassembly 1 (FIG. 1-5), in a reciprocating straight-line pattern 38 (FIG.11), across the short direction of the panel (across the web). Then,after the photomask/platen assembly 39 moves one raster width 40 in thedirection along the web, the optical transfer drive assembly 37 pullsthe optical transfer assembly backwards, in successive reciprocatingscans covering the entire format as the photomask/platen assemblyadvances.

[0068] The constant portion of the optical transfer drive assembly speedprofile 38 (FIG. 11) in the cross-scan direction is adjustable up ordown in speed. In one embodiment it may typically be 10 cm/sec, aprobable maximum around 17 cm/sec. This speed is held nearly constantacross the scan, but there is no need for extreme precision in thisdrive, and there is no need for extreme accelerations at the ends of thestroke. Speed variations within the exposed field only affect exposuredensity, which has considerable latitude. This motion lends itself wellto a cable or band drive 37, two bands being fixed to points on oppositesides of the optical transfer assembly projecting through the center ofgravity and the center of percussion. Energy may be stored onturn-around, using a dashpot or bumper-spring system.

[0069] The photomask/platen assembly 39 (FIG. 12) similarly rides onthree aerostatic air/vacuum bearings 41, 42, 43 upon a portion of thestone block base structure 33, aligned and attached to the lower stoneblock 29 that supports the optical transfer assembly. It also has twoside air/vacuum bearings 35, 36 taking position from the flat, smoothvertical face 34 of the upper stone block 33. As the photomask/platenassembly increments along, these side guide bearings assure that theintermittent motion of the assembly will be carried out in a precisestraight line.

[0070] The photosensitive-coated web 44 is threaded through the machine,from feed roller 45 to take-up roller 46 (FIG. 13), passing across thelower surface of the vacuum platen 47. Immediately before the start ofscanning a new panel, the vacuum platen sucks the web up into firmcontact, so that throughout the frame the two move together.

[0071] The photomask/platen assembly 39 and the section of web that itgrips are driven the width of one raster scan 40 (FIG. 11) in the shortinterval between reciprocating passes 38 of the optical transferassembly 1 across the format. This intermittent forward movement 40 isabout 80 mm, the height of the good field when an optical system such asthe example given herein in Table 2 is in use. This intermittent yetfairly precise motion can best be accomplished using a lead screw andstepper motor in an open-loop drive 48.

[0072] After advancing one raster interval (about 80 mm), thephotomask/platen assembly 39 then stops and remains stationary until thenext pass of the optical transfer assembly 1 is completed. Thisintermittent forward motion is repeated eight times completing eightraster passes. After eight passes the photomask/platen assembly 39 hasmoved and carried the section of web 44 that it grips about 25.2 inches.The vacuum platen 47 then releases the web 44 and the photomask/platenassembly 39 returns to its starting position, while the web 44 advancesa frame. At that point the vacuum platen again sucks the web downfirmly, and is ready to repeat the cycle.

[0073] Reasonable precision is required in this platen advance toprevent banding in the exposure due to uneven overlap of the contiguousoptical fields.

[0074] There must be a free loop of web material at least 26-30 incheslong 49 (FIG. 13) existing at the feeder end of the platen at the startof a frame, and the first pass of raster scanning most convenientlystarts at the take-up end of the frame. This free loop of web materialwill be transferred to the take-up end of the roll-to-roll assembly 50as the photomask/platen assembly intermittently moves forward and theraster scan proceeds.

[0075] The geometrical squareness of the machine and of the pattern thatit records depends upon the accuracy with which the vertical referenceface 34 of the upper part of the stone base structure and the verticaloptics guide plate 32 on the lower part of the stone base structure arelined up perpendicular to each other. To the degree that they areskewed, this skewness will be imparted to every pattern which the systemwrites. The recorded pattern is not degraded in any other major way bythis error, so long as it is kept small.

[0076] Both the object field 7 and the image field 8 (FIG. 1-5) must bemaintained in good focus throughout the optical pass. Directly aboveeach of the two front air/vacuum bearings 26, 27 (FIG. 3, 4) supportingthe optical transfer assembly, there is a servoed lifter, for example apiezo actuator or a microstepper 51, 52 that is capable of raising orlowering that side of the optical system by ±50μ. Each actuator doesthis in closed-loop response to sensor signals received from proximitygages 52, 53 directly above which monitor the distance between theoptical transfer assembly 1 and the photomask object plane 7 on one sideand the format image plane 8 on the other (FIG. 3). The third lifter 55,above the rear bearing 28, is slaved to the average of the other twolifters 51 and 52. The piezo lifters 51, 52, 55 can optionally bereplaced by linear microstepper motors which have a least count of 0.1μor better.

[0077] A number of air proximity gages exist which can be employed forautofocus (Refs. 8, 16). Air gages operate at extremely lowoverpressure, a pressure regime where the airflow is essentiallynon-compressible, and the gage is, consequently, extremely rapid inresponse (Ref. 16). Typically response will exceed 100 Hz. Thisprinciple has been used for autofocus proximity sensing since theearliest wafer steppers. Alternatively laser triangulation gages areoffered commercially which are sufficiently fast and accurate for thispurpose, and astigmatic gages are available which are more thansufficiently fast and accurate to maintain this focus. FIGS. 17 and 18illustrate the astigmatic image and the operating precision of one suchastigmatic gage. In FIG. 17 the five spot distributions show changingray patterns when the format distance changes. The quadrant detector inthe gage and its circuit sensitively picks up the change in imageaspect, by continuously solving the fraction (A+C)−(B+D)/(A+B+C+D). Thedenominator normalizes the result so that the device is insensitive toformat reflectivity. FIG. 18 shows the computed optical signal responsecurve for the proximity detector design TESTASTG.006.

[0078] The autofocus system needs to be preset to a correct focalposition, with the conjugates of the optical transfer assembly set toapproximately equal length, so that the magnification is very close toone. This adjustment is performed grossly by placing a test object inthe photomask object plane, and directly observing an in-focus image ofthat object in the image plane, superimposed upon another dimensionallyidentical version of that object. Slight out of focus does not matter inthis test, since the optical transfer optical system is designed to betelecentric. A calibrated series of test exposures is run at slightlydifferent magnifications and focal settings, first evaluated using a CCDcamera, then with an SEM. A central magnification and optimum focalsetting are chosen. The focal setting is the center position that theair gages attempt to maintain thereafter. As subsequent layers build upthe format thickness the focal position is changed suitably tocompensate for the new image level. Initial focusing instrumentationsimilar to that described by Markle, Ref. 11, can also be used to setthe zero positions of the autofocus sensor gages.

[0079] The photomask and platen assembly 39 carries both the photomaskframe 65 and the vacuum platen 66 in one unit, which is supported onthree aerostatic air/vacuum bearings 41, 42, 43. The assembly is shown,highly stylized, in FIG. 12. It requires a truss design so that itdoesn't sag an unacceptable amount in the middle. Uncorrected sag causesthe optical system to compensate via autofocus in order for the image toremain in sharp focus. The photomask subassembly 67 (FIG. 19) comprisesa large sheet of glass or quartz carrying the master pattern 68,weighing perhaps 30 pounds, held in an outer frame 65, and within thatan inner frame 69, with piezo or microstepper drivers bearing on thesides 70 or bottom 71, 72 of the inner frame. For photomasks as large as24″ and as thick as 0.75 inches, the very small sag of the mask itself,excluding the sag of the mounting frame, is easily overcome by thedynamic focussing action of the proximity autofocus gage 53 and servolifter 51 underlying the object field. Suitable photomasks for thisapplication are made to order by Micronic of Taby, Sweden, or by a laserwriting machine of their manufacture.

[0080] Alignment gages read the position of the object at which they arepointed relative to the axis of the gage, in either X or Y (or both),and output the result as a voltage. There are a number of gages known inthe art that can be employed to sense the alignment of the fiducials toa required accuracy of about 0.2 microns. Most are based upon the use ofCCD sensors, for example Reticons. Others employ modulated sources andposition sensitive silicon detectors (PSD's).

[0081] One good design of a PSD based position detector employs a redlaser light source, modulated at approximately 10 KHz, located behindand illuminating a transparent fiducial. The image of this fiducialfalls on the position sensitive silicon detector, and is synchronouslydemodulated using the same 10 KHz clock which modulates the source. Thesignal-to-noise and hence the position accuracy is further enhanced bycombining a number of rapid sequential readings in a simple BASICprogram. Because of the synchronous demodulation and the individualfree-running 10 KHz oscillators (which, because of different components,actually run at slightly different frequencies), there is no cross-talkbetween gages, even when they are located close together.

[0082] The sensor or receiver portion of the gages 86 are located in themoving optical transfer assembly, with their targets 61-64, 73-76located on the photomask and the web format respectively and with themodulated illuminators 87 located in the photomask/platen assembly.

[0083] Alignment gages are used when one is writing a second or higherlayer over the first recorded pattern or layer that exists on the web.In that situation it is necessary that the subsequent patterns superposeover the base pattern accurately enough so that the functionalcharacteristics of the circuit are maintained. In a panel this mayrequire accuracy in superposition to around 1 micron. A plastic formatplane as large as 18×24 inches is liable to severe and essentiallyunpredictable distortion, estimated to be as large as 1 part in 10⁴, dueto humidity, heat, mechanical stretching and processing. This error canamount to 50 microns or more. The occurrence of at least 10-20 micronsof distortion is expected.

[0084] The position and size of various areas of a previously writtenpattern must be measured immediately before each of the subsequentlayers is recorded. Alignment marks or fiducials are recorded at 80 mm.intervals along both sides of the first layer when it is originallywritten. Similar alignment marks are included at corresponding positionson the photomasks describing the subsequent layers.

[0085] Two position sensitive gages are carried at each end of theoptical transfer assembly. One gage 57 is located on the object end atthe level of the center of the optical field, and another 63 is locatedone field width (80 mm) below it (FIG. 16). Similarly, at the image end,one gage 58 is located at the level of the center of the image field,and one gage 60 is located 80 mm. below it. Fiducial marks, which thesegages use as targets, are located in corresponding positions at the leftand at the right, on both the mask 61, 63, 73, 75 and on the format 62,64, 74, 76.

[0086] When a new frame commences, the web 44 is first sucked down tothe platen 47, in a nearly correct position. If this is the first layerto have been recorded upon this format, the first recording passcommences immediately after the web is sucked down. If it is a second orsubsequent layer, the optical transfer assembly must make a firstalignment pass, enabling the photomask/format registration and thesystem magnification to be adjusted to the starting registrationposition and distortion value, prior to recording the first exposurepass. At the start of the first pass the positions of the first fourfiducials are read, at the left on the level of the middle of the objectfield 61, on the format at the left at the middle of the image field 62,and the two fiducials 80 mm below at the left on the mask 63 and on theformat 64. These values read by the gages are remembered by the system.At the end of the first pass four more fiducials are read, those on theright at the level of the centers of the object and image fields, 73, 74and those 80 mm. below, 75 and 76.

[0087] There is foreknowledge of the separation between the fiducialpairs 61, 63 and 63, 75 on the photomask, in both X and Y. Thereforecomparison of these four known positions with the four unknown positions62, 64, 74, 76 (comparing the positions of eight fiducials) gives ameasure of the distortion that exists in both directions, X and Y, atthe start of scan as well as the mask/format misalignment.

[0088] The first task is to place the upper left comer of the photomaskin correct registry sideways and up and down with respect to the web, asmeasured by the corresponding gage on the image side. This compriseslining up the images (FIG. 16) of the top left fiducial 61 of thephotomask pattern with the top left fiducial 62 of the format pattern inboth X and Y and the top right fiducials 73, 74 in Y only. This maneuverrequires incremental motion in both X using the Δx piezo driver 70 and Yusing the two Δy piezo drivers 71, 72 (FIG. 19) which are spaced alongthe bottom edge of the frame. Alignment may also require a slightrotation of the photomask, which requires the two drivers 71, 72 to actin opposite directions. At the point where top left X and Y errorsbetween 61 and 62 are removed, any difference in coincidence that mayexist between the X positions of the images of the far right fiducials73, 74 is a distortion in X which exists between the previously writtenformat pattern and the second layer photomask. Differences that mayexist at that point in both X and Y image positions (63 vs. 64 and 75vs. 76) as observed at both the left and right lower fiducial pairssignal both an X distortion and a Y distortion.

[0089] As the optical transfer assembly passes across its track, layingdown the first recorded pass of the second layer, the Δx driver element70, acting linearly in concert, moves the photomask slightly in X, plusor minus, a total of exactly the amount of the discrepancy that thegages have measured in X between the two top right hand comer fiducials73, 74 of the photomask and the format. The addition of this smallcomponent of X motion (Δx) insures that the image, which was exactly inregistry at the start of the scan, will again be exactly in registry atthe end of the scan. At the end of the recording pass thephotomask/vacuum platen assembly 39 moves incrementally ahead, advancing80 mm so that the format and photomask will be positioned correctly forthe next pass, with appropriate overlap. At this point the gages cansee, on both the mask and the format, the next set of fiducials, 160 mm.down the mask and the format, and from the new displacement readings candeduce the new X and Y distortion and magnification error that exists inthat upcoming region of previously recorded imagery.

[0090] This process is substantially repeated on each reciprocal opticalpass, except that the sense of the small Δx correction which is appliedis reversed. This plus or minus Δx correction is inserted as required oneach subsequent pass of the optical transfer assembly across the format.The amount of incremental Δx distance that is added varies from scanpass to scan pass, according to the X readings that have been read andremembered by the alignment gages.

[0091] Similarly, the Y direction actuators 71, 72 correct small Δyerrors. Differential Δy motion increments, due to format distortion andmeasured at the start of the pass, are added as linear incrementalmotion to the photomask, within its assembly, during each cross-scan.

[0092] Since the photomask and the platen are incorporated in oneassembly 39, retained by guide bearings 35, 36 which reference to thevertical face 34 of the stone base structure 33, if one is moved in Ythe approximate distance of one scan width, the other moves the samedistance as well. If there is sufficient distance between the twobearings 35 and 36 no yaw error will develop from this movement.

[0093] Correcting for X and Y distortion as described above places thecentral point of the instantaneous optical field at exactly the correctposition throughout each scan and throughout the entire raster pattern,to a first approximation. However, it does not correct the recordedposition of the top and bottom edges of the optical field to the degreethat may be necessary. This effect can be illustrated by using (anextreme) numerical example. Suppose that the total measured Δy errorfrom one pass to the next whose center-line was 80 mm removed was plus 8microns, a distortion of 1 part in 10⁴. This would mean that the imagewas, at each extreme, minus 4 microns out at the top of the opticalfield position, and plus 4 microns out at the bottom of the same field.The image of the photomask object is slightly too small to correspondwith the previous pattern exactly except at the center, without sizecorrection.

[0094] A slight increase in the system magnification from one pass tothe next (1 part in 10⁴) will, to a first approximation, fix this error.As explained earlier, small changes in magnification are introduced intothe 1:1 reflective optical system by moving one mirror of the primarypair forward very slightly on its flex joint mounting, and the otherbackward. The second optical system example presented here, Table 2, hasa field approximately 80 mm. in arc length, or 80,000 microns.Compensation for the −4 micron error in the numerical example aboverequires a system magnification increase of ΔM≅1×10⁻⁴ which isaccomplished by moving the first primary mirror 4 forward, shorteningits conjugate distance, and moving the second primary mirror 5 backward,lengthening its conjugate distance. The optical system design is capableof more than 10 times this change without losing optical quality.

[0095] Prior to the start of each recording pass the optical systemadjusts its configuration slightly as described above, moving one of theprimary mirrors forward a very small amount and the other mirrorbackward an equal amount. This changes the magnification of the system avery small amount to reduce the upcoming Δy error.

[0096] The system controller 56 (FIG. 14) is a multi-axis motorcontroller typically made by Oregon Micro Systems. Working inconjunction with the system computer, it switches from one drivefunction to another as necessary to command the two drive components ofthe scan pattern, the piezo drivers for the photomask alignment andfocus, and the web drive. This is schematically illustrated in FIG. 14.

[0097] System productivity depends upon a number of factors, e.g,operating speed, length of the flexible web and how often the systemmust be reloaded, the type and thickness of the photoresist or otherphotosensitive material. A reasonable upper limit for machine throughputwould be the production of 100 18″×24″ panels per hour. Assuming the useof 1000 ft. rolls of flexible material, and allowing time to change therolls about twice per shift, leads to the requirement that the opticaltransfer assembly must scan the photomask and format at a speed around15 cm/second (with appropriate allowances for overrun and turnaroundtimes). This speed is very reasonable.

[0098] Although a number of forms and expedients have been shown anddescribed, the invention is not limited thereto but includes allmodifications and variations within the scope of the appended claims.

Appendix 1 Other References Cited

[0099] 1. “Unit Magnification Optical System without SeidelAberrations”, J. Dyson, JOSA, Vol. 49, No. 7, July, 1959, pp. 713-716

[0100] 2. U.S. Pat. No. 3,748,015, Abe Offner, dated Jul. 24, 1973,“Unit Power Imaging Catoptric Anastigmat”

[0101] 3. U.S. Pat. No. 3,821,763, Roderic M. Scott, dated Jun. 28,1974, “Annular Field Optical Imaging System”

[0102] 4. U.S. Pat. No. 3,884,573, David M. Franklin, dated May 20,1975, “Apparatus for High Resolution Projection Printing”

[0103] 5. U.S. Pat. No. 3,951,546, David A. Markle, dated Apr. 20, 1976,“Three-Fold Mirror Assembly for a Scanning Projection System”

[0104] 6. U.S. Pat. No. 4,011,011, Harold S. Hemstreet et al, dated Mar.8, 1977, “Optical Projection Apparatus”

[0105] 7. U.S. Pat. No. 4,068,947, Jere D. Buckley et al, dated Jan. 17,1978, “Optical Projection and Scanning Apparatus”

[0106] 8. U.S. Pat. No. 4,142,401, Gardner P. Wilson, dated Mar. 6,1979, “Gage”

[0107] 9. U.S. Pat. No. 4,171,870, John H. Bruning et al, dated Oct. 23,1979, “Compact Image Projection Apparatus”

[0108] 10. U.S. Pat. No. 4,241,390, David A. Markle, dated Dec. 23,1980, “System for Illuminating an Annular Field”

[0109] 11. U.S. Pat. No. 4,549,084, David A. Markle, dated Oct. 22,1985, “Alignment and Focusing System for a Scanning Mask Aligner”

[0110] 12. U.S. Pat. No. 4,650,315, David A. Markle, dated Mar. 17,1987, “Optical Lithographic System”

[0111] 13. U.S. Pat. No. 4,779,966, Irwin Friedman, dated Oct. 25, 1988,“Single Mirror Projection Optical System”

[0112] 14. U.S. Pat. No. 4,924,257, Kantilal Jain, dated May 8, 1990,“Scan and Repeat High Resolution Projection Lithography System”

[0113] 15. U.S. Pat. No. 4,933,714, Jere D. Buckley et al, dated Jun.12, 1990, “Apparatus and Method for Reproducing a Pattern in an AnnularArea”

[0114] 16. U.S. Pat. No. 4,953,388, Andrew H. Barada, dated Sept. 14,1990, “Air Gauge Sensor”

[0115] 17. U.S. Pat. No. 5,103,257, Roloef Wijnasendts-van-Resandt,dated Apr. 7, 1992, “Process for Producing or Inspecting Micropatternson Large-Area Substrates”

[0116] 18. U.S. Pat. No. 5,227,839, Paul C. Allen, dated Jul. 13, 1993,“Small Field Scanner”

[0117] 19. U.S. Pat. No. 5,285,236, Kanti Jain, dated Feb. 8, 1994,“Large-Area High-Throughput, High-Resolution Projection Imaging System”

[0118] 20. U.S. Pat. No. 5,329,332, David A. Markle et al, dated Jul.12, 1994, “System for Achieving a Parallel Relationship Between Surfacesof Wafer and Reticle or Half-Field Dyson Stepper”

[0119] 21. “A Large Flat Panel Printer”, T. R. Whitney, presented to theSociety for Imaging Science and Technology 49^(th) Annual Conference May19-24, 1996

[0120] 22. U.S. Pat. No. 5,530,516, Ronald E. Sheets, dated Jun. 25,1996, “Large-Area Projection Exposure System”

[0121] 23. U.S. Pat. No. 5,559,629, Ronald E. Sheets et al, dated Sep.24, 1996, “Unit Magnification Projection System and Method”

[0122] 24. U.S. Pat. No. 5,585,972, David A. Markle, dated Dec. 17,1996, “Arbitrarily Wide Lens Array with an Image Field to Span the Widthof a Substrate”

[0123] 25. U.S. Pat. No. 5,652,645, Kanti Jain, dated Jul. 29, 1997,“High-Throughput, High-Resolution, Projection Patterning System forLarge, Flexible Roll-Fed, Electronic-Module Substrates”

[0124] 26. U.S. Pat. No. 5,710,619, Kanti Jain, dated Jan. 20, 1998,“Large-Area, Scan-and-Repeat, Projection Patterning System with UnitaryStage and Magnification Control Capability”

[0125] 27. U.S. Pat. No. 5,729,331, Masashi Tanaka et al, dated Mar. 17,1998, “Exposure Apparatus, Optical Projection Apparatus and a Method forAdjusting the Optical Projection Apparatus”

[0126] 28. U.S. Pat. No. 5,739,964, Paul C. Allen, dated Apr. 14, 1998,“Magnification Correction for Small Field Scanning”

[0127] 29. U.S. Pat. No. 5,781,346, Paul C. Allen et al, dated Jul. 14,1998, “Magnification Correction for Small Field Scanning”

[0128] 30. U.S. Pat. No. 6,018,383, Thomas J. Dunn et al, dated Jan. 25,2000, “Very Large Area Patterning System for Flexible Substrates”

[0129] 31. U.S. Pat. No. 6,084,706, John M. Tamkin et al, dated Jul. 4,2000, “High Efficiency Pattern Generator”

[0130] 32. U.S. Pat. No. 6,304,315 B2, David Kessler et al, dated Oct.16, 2001, “High Speed High Resolution Continuous Optical Film Printerfor Duplicating Motion Films” TABLE 1 RLE ID ALL MIRROR SYSTEM,1X1REFLECT.006 ID1 F/NUM 3.449, COMPLETELY OFFNER SYSTEM ID2 ALL SPHERESID3 ABOUT 18 INCHES BETWEEN FIELD CENTER LINES ID4 ARCTUATE FIELDINSTALLED AS UAP 4, ID5 122.29 MM. ARC RADIUS. FIELD WIDTH 1X30 MM. WAVL.3650000 .4040000 .4380000 APS −22 GLOBAL XPXT UNITS MM OBJ FINITE−0.24140259 4.00000000 15.00000000 REF HEIGHT −0.03500000 4.00003140−0.03500000 15.00011774 MARGIN 1.270000 BEVEL 0.254001  0 AIR  1 CV0.0000000000000 TH 0.00000000  1 -AIR  2 UAP 4 8 15.00000000 −0.540000008.00000000 0.54000000 −8.00000000 0.54000000 −15.00000000 −0.54000000−15.00000000 −1.54000000 −8.00000000 −0.54000000 8.00000000 −0.5400000015.00000000 −1.54000000  2 CV 0.0000000000000 TH 0.00000000  2 -AIR  3CV 0.0000000000000 TH −80.00000000  3 -AIR  4 CV 0.0000000000000 TH0.00000000  4 -AIR  5 CV 0.0000000000000 TH −59.90240000  5 -AIR  6 RAO120.00000000 60.00000000 −10.00000000 0.00000000  6 CV 0.0000000000000TH 0.00000000  6 AIR  6 DECEN 0.00000000 0.00000000 0.00000000 200  6 BT45.00000092 0.00000000 200  6 EFILE EX1 31.270000 31.270000 31.5240000.000000  6 EFILE EX2 31.270000 31.270000 0.000000  6 EFILE MIRROR−10.000000  7 CV 0.0000000000000 TH 0.00000000  7 AIR  7 DECEN0.00000000 0.00000000 0.00000000 200  7 BT 45.00000092 0.00000000 200  8CV 0.0000000000000 TH 0.00000000  8 AIR  9 CV 0.0000000000000 TH0.00000000  9 AIR 10 CV 0.0000000000000 TH 122.29000000 10 AIR 10 DECEN0.00000000 0.00000000 0.00000000 99 10 AT 0.00000000 0.00000000 99 11RAO 120.00000000 120.00000000 0.00000000 −8.00000000 11 CV0.0000000000000 TH 0.00000000 11 -AIR 11 DECEN 0.00000000 0.000000000.00000000 200 11 AT 45.00000107 0.00000000 200 11 EFILE EX1 61.27000061.270000 61.524000 0.000000 11 EFILE EX2 61.270000 61.270000 0.00000011 EFILE MIRROR 12.500000 12 CV 0.0000000000000 TH −442.33584756 12 -AIR12 DECEN 0.00000000 0.00000000 0.00000000 200 12 AT 45.000001070.00000000 200 13 RAO 240.00000000 218.00000000 0.00000000 108.0000000013 CV 0.0014062460552 TH 351.39880915 13 AIR 13 DECEN 0.00000000−108.00000000 0.00000000 200 13 AT 0.00000000 0.00000000 200 13 EFILEEX1 110.270000 110.270000 110.270000 0.000000 13 EFILE EX2 110.270000110.270000 0.000000 13 EFILE MIRROR −10.900000 14 CV 0.0000000000000 TH0.00000000 14 AIR 15 CV 0.0000000000000 TH 0.00000000 15 AIR 16 CV0.0000000000000 TH 0.00000000 16 AIR 17 CV 0.0000000000000 TH 0.0000000017 AIR 18 CV 0.0000000000000 TH 0.00000000 18 AIR 19 CV 0.0000000000000TH 0.00000000 19 AIR 20 CV 0.0000000000000 TH 0.00000000 20 AIR 20 DECEN0.00000000 0.00000000 0.00000000 1 20 GT 90.00000000 0.00000000 1 21 CV0.0000000000000 TH 0.00000000 21 AIR 22 RAD 356.1697137266146 TH0.00000000 22 -AIR 22 DC1 0.0000000E+00 0.0000000E+00 0.0000000E+000.0000000E+00 0.0000000E+00 22 DC2  0.00000E+00  0.00000E+00 0.00000E+00  0.00000E+00  0.00000E+00  0.00000E+00 22 DC3  0.00000E+00 0.00000E+00  0.00000E+00  0.00000E+00  0.00000E+00  0.00000E+00 22DECEN 0.00000000 0.00000000 0.00000000 99 22 AT 0.00000000 0.00000000 9922 EFILE EX1 49.000000 50.000000 50.000000 0.000000 22 EFILE EX249.000000 49.000000 0.000000 22 EFILE MIRROR 12.500000 23 CV0.0000000000000 TH 0.00000000 23 -AIR 23 DECEN 0.00000000 0.000000000.00000000 1 23 AT 0.00000000 0.00000000 1 24 CV 0.0000000000000 TH0.00000000 24 -AIR 25 CV 0.0000000000000 TH 0.00000000 25 -AIR 26 CV0.0000000000000 TH 0.00000000 26 -AIR 27 CV 0.0000000000000 TH0.00000000 27 -AIR 28 PTH −21 1.00000000 0.00000000 28 CV0.0000000000000 28 -AIR 29 PCV 21 1.00000000 0.00000000 29 PTH −201.00000000 0.00000000 29 PIN −20 29 GID ‘PICKUP’ 30 PCV 20 1.000000000.00000000 30 PTH −19 1.00000000 0.00000000 30 -AIR 31 PCV 19 1.000000000.00000000 31 PTH −18 1.00000000 0.00000000 31 PIN −18 31 GID ‘PICKUP’32 PCV 18 1.00000000 0.00000000 32 PTH −17 1.00000000 0.00000000 32 -AIR33 PCV 17 1.00000000 0.00000000 33 PTH −16 1.00000000 0.00000000 33 PIN−16 33 GID ‘PICKUP’ 34 PCV 16 1.00000000 0.00000000 34 PTH −151.00000000 0.00000000 34 -AIR 35 PCV 15 1.00000000 0.00000000 35 PTH −141.00000000 0.00000000 35 PIN −14 35 GID ‘PICKUP’ 36 PCV 14 1.000000000.00000000 36 PTH −13 1.00000000 0.00000000 36 -AIR 37 PCV 13 1.000000000.00000000 37 RAO 240.00000000 218.00000000 0.00000000 −108.00000000 37TH 462.33584756 37 AIR 37 EFILE EX1 110.270000 110.270000 110.5240010.000000 37 EFILE EX2 110.270000 110.270000 0.000000 37 EFILE MIRROR−10.900000 38 RAO 120.00000000 120.00000000 0.00000000 8.00000000 38 CV0.0000000000000 TH 0.00000000 38 -AIR 38 DECEN 0.00000000 −108.000000000.00000000 200 38 AT 45.00000106 0.00000000 200 38 EFILE EX1 61.27000061.270000 61.524000 0.000000 38 EFILE EX2 61.270000 61.270000 0.00000038 EFILE MIRROR 12.500000 39 CV 0.0000000000000 TH 0.00000000 39 -AIR 39DECEN 0.00000000 0.00000000 0.00000000 200 39 AT 45.00000106 0.00000000200 40 CV 0.0000000000000 TH 0.00000000 40 -AIR 41 CV 0.0000000000000 TH−122.29000000 41 -AIR 42 RAO 120.00000000 60.00000000 −10.000000000.00000000 42 CV 0.0000000000000 TH 0.00000000 42 AIR 42 DECEN0.00000000 0.00000000 0.00000000 200 42 BT −45.00000092 0.00000000 20042 EFILE EX1 31.270000 31.270000 31.524000 0.000000 42 EFILE EX231.270000 31.270000 0.000000 42 EFILE MIRROR −10.000000 43 CV0.0000000000000 TH 59.90240000 43 AIR 43 DECEN 0.00000000 0.000000000.00000000 200 43 BT −45.00000092 0.00000000 200 44 CV 0.0000000000000TH 0.00000000 44 AIR 45 CV 0.0000000000000 TH 0.00000000 45 AIR 46 CV0.0000000000000 TH 0.00000000 46 AIR 47 CV 0.0000000000000 TH 0.0000000047 AIR 48 CV 0.0000000000000 TH 80.00000000 48 AIR 49 CV 0.0000000000000TH 0.24140259 49 AIR 50 CV 0.0000000000000 TH 0.00000000 50 AIR 51 CV0.0000000000000 TH 0.00000000 51 AIR END SYNOPSYS AI>

[0131] TABLE 2 RLE ID PRP 20 VERSION 1.8 USING ASPHERIC ID1 F/NUM 4.05BY 4.85, FROM VERSION 1.7 ID2 ASPHERIC PUPIL, ARC FIELD STOP FEATHEREDID3 ABOUT 19.3 INCHES BETWEEN FIELD CENTER LINES ID4 122.0 MM. ARCRADIUS. FIELD WIDTH 4X80 MM. WAVL .3650000 .4040000 .4380000 APS −21GLOBAL XPXT EPUPIL NOVIG UNITS MM OBJ FINITE −0.24140259 2.0000000040.00000000 REF HEIGHT −0.02500000 2.00002315 −0.03000000 40.00046302MARGIN 1.270000 BEVEL 0.254001  0 AIR  1 CAO 124.00000000 0.00000000−122.00000000  1 CAI 120.00000000 0.00000000 −122.00000000  1 CV0.0000000000000 TH 0.00000000  1 -AIR  2 UAP 4 4 40.10000000 2.1000000040.10000000 −4.70000000 −40.10000000 −4.70000000 −40.10000000 2.10000000 2 CV 0.0000000000000 TH −136.06343000  2 -AIR  3 RAO 180.0000000060.00000000 10.00000000 0.00000000  3 CV 0.0000000000000 TH 0.00000000 3 AIR  3 DECEN 0.00000000 0.00000000 0.00000000 200  3 BT −45.000000550.00000000 200  3 EFILE EX1 31.270000 31.270000 31.524000 0.000000  3EFILE EX2 31.270000 31.270000 0.000000  3 EFILE MIRROR −10.000000  4 CV0.0000000000000 TH 113.83900000  4 AIR  4 DECEN 0.00000000 0.000000000.00000000 200  4 BT −45.00000055 0.00000000 200  5 RAO 155.0001000095.00000000 0.00000000 −5.00000000  5 CV 0.0000000000000 TH 0.00000000 5 -AIR  5 DECEN 0.00000000 0.00000000 0.00000000 200  5 AT 45.000001610.00000000 200  5 EFILE EX1 48.770000 48.770000 49.024000 0.000000  5EFILE EX2 48.770000 48.770000 0.000000  5 EFILE MIRROR 10.000000  6 CV0.0000000000000 TH 0.00000000  6 -AIR  6 DECEN 0.00000000 0.000000000.00000000 200  6 AT 45.00000161 0.00000000 200  7 CV 0.0000000000000 TH0.00000000  7 -AIR  8 CV 0.0000000000000 TH 0.00000000  8 -AIR  9 CV0.0000000000000 TH −96.27020000  9 -AIR 10 RAO 190.00020000 130.000000000.00000000 −5.00000000 10 CV 0.0000000000000 TH 0.00000000 10 AIR 10DECEN 0.00000000 0.00000000 0.00000000 200 10 AT −45.00000176 0.00000000200 10 EFILE EX1 66.270000 66.270000 66.524000 0.000000 10 EFILE EX266.270000 66.270000 0.000000 10 EFILE MIRROR −10.000000 11 CV0.0000000000000 TH 340.18700000 11 AIR 11 DECEN 0.00000000 0.000000000.00000000 200 11 AT −45.00000176 0.00000000 200 12 RAO 255.00000000170.00000000 0.00000000 122.00000000 12 CV −0.0014660357817 TH−335.38433884 12 -AIR 12 DECEN 0.00000000 −122.00000000 0.00000000 20012 AT 0.00000000 0.00000000 200 12 EFILE EX1 86.270000 86.27000086.524001 0.000000 12 EFILE EX2 86.270000 86.270000 0.000000 12 EFILEMIRROR 8.500000 13 CV 0.0000000000000 TH 0.00000000 13 -AIR 14 CV0.0000000000000 TH 0.00000000 14 -AIR 15 CV 0.0000000000000 TH0.00000000 15 -AIR 16 CV 0.0000000000000 TH 0.00000000 16 -AIR 17 CV0.0000000000000 TH 0.00000000 17 -AIR 18 CV 0.0000000000000 TH0.00000000 18 -AIR 19 CV 0.0000000000000 TH 0.00000000 19 -AIR 19 DECEN0.00000000 0.00000000 0.00000000 1 19 GT −90.00000086 0.00000000 1 20 CV0.0000000000000 TH 0.00000000 20 -AIR 21 RAD −384.3771101406386 TH0.00000000 21 CC −0.95921965 21 AIR 21 DC1 −1.6015744E−04 −3.0107985E−09−3.9049472E−14 1.4301874E−17 −2.6293285E−21 21 DC2    0.00000E+00   0.00000E+00    0.00000E+00  0.00000E+00    0.00000E+00    0.00000E+0021 DC3    0.00000E+00    0.00000E+00    0.00000E+00  0.00000E+00   0.00000E+00    0.00000E+00 21 DECEN 0.00000000 0.00000000 0.0000000099 21 AT 0.00000000 0.00000000 99 21 EFILE EX1 49.000000 50.00000050.000000 0.000000 21 EFILE EX2 49.000000 49.000000 0.000000 21 EFILEMIRROR −12.500000 22 CV 0.0000000000000 TH 0.00000000 22 AIR 22 DECEN0.00000000 0.00000000 0.00000000 1 22 AT 0.00000000 0.00000000 1 23 CV0.0000000000000 TH 0.00000000 23 AIR 24 CV 0.0000000000000 TH 0.0000000024 AIR 25 CV 0.0000000000000 TH 0.00000000 25 AIR 26 CV 0.0000000000000TH 0.00000000 26 AIR 27 PTH −20 1.00000000 0.00000000 27 CV0.0000000000000 27 AIR 28 PCV 20 1.00000000 0.00000000 28 PTH −191.00000000 0.00000000 28 PIN −19 28 GID ‘PICKUP’ 29 PCV 19 1.000000000.00000000 29 PTH −18 1.00000000 0.00000000 29 AIR 30 PCV 18 1.000000000.00000000 30 PTH −17 1.00000000 0.00000000 30 PIN −17 30 GID ‘PICKUP’31 PCV 17 1.00000000 0.00000000 31 PTH −16 1.00000000 0.00000000 31 AIR32 PCV 16 1.00000000 0.00000000 32 PTH −15 1.00000000 0.00000000 32 PIN−15 32 GID ‘PICKUP’ 33 PCV 15 1.00000000 0.00000000 33 PTH −141.00000000 0.00000000 33 AIR 34 PCV 14 1.00000000 0.00000000 34 PTH −131.00000000 0.00000000 34 PIN −13 34 GID ‘PICKUP’ 35 PCV 13 1.000000000.00000000 35 PTH −12 1.00000000 0.00000000 35 AIR 36 PCV 12 1.000000000.00000000 36 RAO 255.00000000 170.00000000 0.00000000 −122.00000000 36TH −331.26900000 36 -AIR 36 EFILE EX1 86.270000 86.270000 86.5240010.000000 36 EFILE EX2 286.270000 86.270000 0.000000 36 EFILE MIRROR8.500000 37 RAO 190.00020000 130.00000000 0.00000000 0.00000000 37 CV0.0000000000000 TH 0.00000000 37 AIR 37 DECEN 0.00000000 −122.000000000.00000000 200 37 AT −45.00000175 0.00000000 200 37 EFILE EX1 66.27000066.270000 66.524000 0.000000 37 EFILE EX2 66.270000 66.270000 0.00000037 EFILE MIRROR −10.000000 38 CV 0.0000000000000 TH 92.89800000 38 AIR38 DECEN 0.00000000 0.00000000 0.00000000 200 38 AT −45.000001750.00000000 200 39 CV 0.0000000000000 TH 0.00000000 39 AIR 40 CV0.0000000000000 TH 182.19200000 40 AIR 41 CV 0.0000000000000 TH0.00000000 41 AIR 42 CV 0.0000000000000 TH 0.00000000 42 AIR 43 CV0.0000000000000 TH 0.00000000 43 AIR 44 CV 0.0000000000000 TH 0.0000000044 AIR 45 CV 0.0000000000000 TH 80.00000000 45 AIR 46 CV 0.0000000000000TH −220.69057000 46 AIR 47 RAO 169.99965000 95.00000000 0.00000000−5.00000000 47 CV 0.0000000000000 TH 0.00000000 47 -AIR 47 DECEN0.00000000 0.00000000 0.00000000 200 47 AT −45.00000055 0.00000000 20047 EFILE EX1 48.770000 48.770000 49.024000 0.000000 47 EFILE EX248.770000 48.770000 0.000000 47 EFILE MIRROR 10.000000 48 CV0.0000000000000 TH −230.93400000 48 -AIR 48 DECEN 0.00000000 0.000000000.00000000 200 48 AT −45.00000055 0.00000000 200 49 CV 0.0000000000000TH 146.06200000 49 -AIR 50 RAO 190.00020000 60.00000000 12.500000005.30000000E−09 50 CV 0.0000000000000 TH 0.00000000 50 AIR 50 DECEN0.00000000 0.00000000 0.00000000 200 50 BT 45.00000052 0.00000000 200 50EFILE EX1 31.270000 31.270000 31.524000 0.000000 50 EFILE EX2 31.27000031.270000 0.000000 50 EFILE MIRROR −10.000000 51 CV 0.0000000000000 TH136.06343000 51 AIR 51 DECEN 0.00000000 0.00000000 0.00000000 200 51 BT45.00000052 0.00000000 200 52 CV 0.0000000000000 TH 0.00000000 52 AIR

1) An optical machine for creating an image of a master object on aformat plane, including: a first assembly defining a master object planeand a format plane in spaced apart positions; a second assembly disposedbetween the master object plane and the format plane, for transferringsuccessive parts of the image of the master object from the plane of themaster object to the format plane; a third assembly which moves thesecond assembly reciprocally in a first direction to provide a firstdimension of an areal scan pattern; a fourth assembly coupled to thefirst and second assemblies for moving the first assembly incrementallyin a second direction orthogonal to the first direction betweenmovements of the second assembly to provide a second dimension of theareal scan pattern. 2) An optical machine according to claim 1 forcreating an image of a master object which is superimposed in registryupon another pre-existing image located in the format plane, wherein thefirst assembly includes means to incrementally move the master objectrelative to the format plane in a controlled manner. 3) An opticalmachine according to claim 1 in which the first assembly contains aphotomask at the master object plane. 4) An optical machine according toclaim 1 in which the first assembly contains a flexible material at theformat plane. 5) An optical machine according to claim 4 in which theflexible material includes a material sensitive to exposure by actinicradiation on at least one side. 6) An optical machine according to claim4 in which the flexible material is one of a class of materialscomprising plastic, thin metal, and a composite membrane. 7) An opticalmachine according to claim 4 in which the flexible material bears apre-existing image. 8) An optical machine according to claim 4 in whichthe flexible material is formed as a web and the system for feeding theweb through the machine comprises a feed roller supplying the flexiblematerial via one or more guide rollers to a take-up roller. 9) Anoptical machine according to claim 8 where the axes of the feed roller,the guide rollers and the take-up roller are aligned parallel to eachother. 10) An optical machine according to claim 8 where are the axes ofthe feed, take-up and guide rollers are parallel and the web moves indirections that are perpendicular to the axes of said rollers. 11) Anoptical machine according to claim 4 including a vacuum platen coupledto the fourth assembly and backing up the flexible material. 12) Anoptical machine according to claim 11 wherein the portion of theflexible web comprising the format area is engaged tightly to the vacuumplaten during completion of a raster scan pattern and moves togetherwith the first assembly during the complete series of passes of thesecond assembly comprising the raster scan pattern. 13) An opticalmachine according to claim 1, wherein the second assembly comprises anoptical transfer assembly. 14) An optical machine according to claim 13in which the second assembly includes means to change the magnificationof the transferred image in a controlled manner 15) An optical machinefor creating an image of a master object on a format plane, including: afirst assembly defining a master object plane as a first component and aformat plane as a second component, the two components beingsubstantially coplanar and in spaced apart positions; a second assemblycomprising an optical transfer subsystem disposed between the objectplane and the format plane, for sequentially transferring successiveparts of the image of the master object from the plane of the masterobject to the format plane; a third assembly comprising a drivemechanism which moves the second assembly reciprocally in a firstdirection to provide a first dimension of a raster scan pattern; afourth assembly comprising a drive mechanism coupled to the first andsecond assemblies for moving the first assembly incrementally in asecond direction orthogonal to the first direction betweenreciprocations of the second assembly to provide a second dimension ofthe raster scan pattern; a fifth assembly comprising a source of actinicradiation, light mixing means and drive means, part of which moves,coupled with the second assembly, to provide actinic radiation to thepart of the image of the master object being transferred; and a basestructure supporting the five assemblies and providing flat andorthogonal reference surfaces for the movements of the first and secondassemblies. 16) An optical machine according to claim 15 wherein thefirst assembly moves intermittently between reciprocating passes of thesecond assembly, and includes aerodynamic bearings referencing off thebase structure, the first assembly being supported and retained to beorthogonal to the reciprocating motion of the second assembly. 17) Anoptical machine according to claim 15 in which the base structurecomprises either stone or metal. 18) An optical machine according toclaim 15 wherein the base structure includes a guide strip which isfirmly mounted and the second assembly includes opposed air bearingsreferencing on the guide strip, and the reciprocating motion of thesecond assembly is thereby guided into a closely repeating path. 19) Anoptical machine according to claim 18 where the guide strip is straightand the closely repeating path followed by the second assembly is astraight-line path. 20) An optical machine according to claim 15,wherein the fifth assembly comprises at least a source of actinicradiation, an integrator rod, a transfer lens and a fiber bundle inseries. 21) An optical machine according to claim 20 in which the sourceof actinic radiation is selected from the class comprising a filamentlamp, a metal-halide arc, a mercury arc, a microwave excited source, anexcimer laser, an ion laser, a light emitting diode, a solid state laseror a gas laser. 22) An optical machine according to claim 20 in whichthe fiber cable is a random arrangement of individual fibers whose exitend is shaped to illuminate the used field of the optical transferassembly and which is driven to illuminate this field throughout thereciprocating pass of the optical transfer assembly. 23) A reflectingoptical system for transferring an image from an object plane to animage plane at nearly unit magnification, comprising a concave mirror, aconvex mirror and a concave mirror in series, the concave mirrors beingspherical, of the same curvature, sharing approximately the same centersand being controllably movable with respect to each other for thepurpose of introducing a slight change in magnification. 24) Areflecting optical system according to claim 23 fitted with a mechanismfor moving the two concave mirrors small amounts in opposing directionsaligned to the axis of the convex mirror in response to driver signalsto change the system magnification. 25) A reflecting optical systemaccording to claim 23 wherein the convex mirror is spherical. 26) Areflecting optical system according to claim 23 wherein the convexmirror is aspherical. 27) A reflecting optical system according to claim23, fitted near to the object plane with an arctuate field stop, thecommon center of the arcs comprising the sides of the stop lying on theaxis of the convex mirror, in order to admit through the reflectingoptical system the arc of rays comprising best imagery. 28) A reflectingoptical system according to claim 23 fitted at the object side with twoorthogonally placed flat mirrors and at the image side with twoorthogonally placed flat mirrors, for inversion and reversion of theimage, the system of flat mirrors combining with the inversion andreversion of the curved reflecting mirrors to produce an erect image.29) A reflecting optical system according to claim 23 fitted at theobject side with three orthogonally placed flat mirrors and fitted atthe image side with three more orthogonally placed flat mirrors, thesystem of flat mirrors combining with the inversion and reversion of thecurved reflecting mirrors to produce an erect image and to rotate thearc of rays comprising best imagery by 90 degrees. 30) A reflectingoptical system according to claim 23, where the system of flat mirrorsis arranged to substantially increase the distance between the center ofthe object plane and the center of the image plane. 31) An opticalmachine for creating an image of a master object on a format plane,including: a first assembly defining a master object plane and a formatplane in spaced apart positions; a second assembly comprising areflecting optical system wherein a concave mirror, a convex mirror anda concave mirror follow each other in series, the concave mirrors beingspherical, of the same curvature, sharing approximately the same centersand being controllably movable with respect to each other for thepurpose of introducing a slight change in magnification, fortransferring successive parts of the image of the master object from theplane of the master object to the format plane at nearly unitmagnification; a third assembly which moves the second assembly in areciprocating motion in a first direction to provide a first dimensionof an areal scan pattern; a fourth assembly coupled to the first andsecond assemblies for moving the first assembly incrementally in asecond direction different from the first between movements of thesecond assembly to provide a second dimension of the areal scan pattern.32) An optical machine according to claim 31 including three air/vacuumbearings supporting the reciprocating motion of the second assembly, onebearing located generally under the object plane, one bearing locatedgenerally under the image plane, and the third bearing located under thecenterline of the convex mirror, removed from the first two bearings toform a triangular support. 33) An optical machine according to claim 32further including two autofocus gages, each generating an error signal,one gage located close to the object plane, monitoring the distance ofthe object plane from the photomask plane and the other gage locatedclose to the image plane, monitoring the distance of the image planefrom the format plane. 34) An optical machine according to claim 33wherein there are three servoed lifters, one above each of theair/vacuum bearings under the object and image planes, wherein eachlifter's movement is responsive to the error signal of the autofocusgage under its respective plane, and the third servo lifter above therear air/vacuum bearing, its drive signal being generated as the averageof the signals driving the other two lifters. 35) An optical machineaccording to claim 31 including a mounting frame movably supporting thephotomask and comprising drivers to permit slight controlled movement intwo orthogonal directions, both directions lying within the objectplane. 36) An optical machine according to claim 31 for creating animage of a master object which is superimposed in registry upon anotherpre-existing image located in the format plane. 37) An optical machineaccording to claim 36, also comprising position sensitive gages carriedon the second assembly which read fiducial marks on the photomask and ona preexisting format image. 38) A method of transferring images whereinan optical machine includes fiducial marks on a photomask and on apreexisting image and the optical machine undergoes successive rasterpasses comprising the steps of reading some fiducial marks on thephotomask and fiducial marks on a pre-existing format image at the startof each raster pass, and reading additional fiducial marks on thephotomask and on the format image at the end of each pass, and derivingfrom the readings knowledge of the distortion existing between selectedpositions on the photomask in X and Y relative to correspondingpositions on the pre-existing format image, and from this knowledgedeveloping driver control signals to progressively move the photomaskwithin its frame during each reciprocating pass of the second assembly.39) A method in accordance with claim 38, wherein the photomaskundergoes slight movement in both X and Y within its frame during araster pass, in response to driver signals to minimize positionalmismatch during the pass between the centers of successive object fieldson the master photomask object and the centers of correspondingsuccessive image fields on the preexisting distorted format image. 40) Amethod in accordance with claim 38 wherein fiducial marks on thephotomask and fiducial marks on a pre-existing format image are read atthe start of each raster pass, and additional fiducial marks on thephotomask and on the pre-existing format image are read at the end ofeach pass, from the readings knowledge is derived of the magnificationerror existing between selected positions on the photomask in X and Y atthe start of successive raster passes relative to correspondingpositions on the pre-existing format image, and from this knowledgedriver control signals are developed to adjust the magnification of theoptical transfer assembly at the start of each raster pass. 41) A methodin accordance with claim 40 in which the optical transfer assemblycomprises two concave mirrors and a convex mirror, and the methodincludes the steps of moving the concave mirrors incrementally inopposite directions aligned to the axis of the convex mirror at thestart of each raster pass to adjust the magnification to compensate theextremes of the instantaneous field for measured Δx and Δy magnificationerrors. 42) A system for recording images on a recording web disposed ina substantially planar disposition between a take-up side and a supplyside and comprising: an areal platen disposed along the web andengageable to a substantial portion of the surface thereof; an imagingsystem disposed between a master object plane and a format plane alongthe width of the web, the imaging system including an illuminatingsource and optics providing a controllable beam for illuminating anobject plane with a portion of an image of the master object; an opticaltransfer assembly for projecting an image of the master object acrossthe web toward the format plane; a first drive for reciprocating theoptical transfer assembly along a first direction substantially equal tothe width of the web such that a first direction of raster scan isprovided at the format plane; a second drive system engaging the vacuumplaten for moving the web laterally relative to the first direction toprovide a two dimensional raster action at the format plane, and a thirddrive means for the recording web for repetitively delineating images ofthe complete master object on successive segments of the web. 43) Asystem for providing precision images of the object on a photomaskcomprising: a web transport system for moving an image web substantiallywithout twisting in a path between a supply region and a take-up region;a web handling device along the web transport system comprising a vacuumplaten engaged against a region of the web and controllably movablealong the direction of movement of the web; an imaging assembly disposedadjacent the web and including a light source, an optical magnificationsystem, and focusing optics disposed in a multi-reflective pathextending across the web path, the imaging assembly being disposed toproject an image of a portion of the photomask at an objective positionon the web; a control system for scanning the imaging assembly across aportion of the photomask in the direction across the web, and a controlsystem for shifting the web incrementally longitudinally relative to thedirection of movement of the optical imaging assembly so as to provide atwo-dimensional raster image of the photomask image. 44) An opticalprojection system for recording images on a photomask serially on arecording web, wherein the recording web is advanced substantiallywithout twisting between supply and takeup sides, comprising: a webtransport system for advancing the web between supply and takeuplocations; an imaging assembly disposed adjacent the web path, theassembly including a radiation source for illuminating a portion of thephotomask, and optics defining a multiply refolded light path, andincluding magnification and focusing controls varying the path length ofthe fields, the light path leading to a format position on the web; afirst raster scanning drive moving the imaging assembly along a firstaxis across the web to provide a first raster scan direction; a secondraster scanning drive moving the web laterally to the first raster scandirection in timed relation to the first raster scan movement, and acontrol system for advancing the web an incremental distance when acomplete raster has been provided. 45) The method of providing highprecision images on an optical recording medium corresponding to amaster image, comprising the steps of: extending the recording mediumalong a recording plane, periodically advancing the recording mediumalong the plane to successive recording positions; illuminating a partof the master object to provide an image beam; repetitively scanning theilluminated part of the master object onto an area of the recordingmedium, with the recording medium stationary; shifting the recordingmedium laterally between scans to provide a two dimensional image on themedium, and advancing the medium along the recording plane when the twodimensional image has been formed. 46) The method of opticallyreproducing the image of a master element with high resolution on arecording medium, comprising the steps of: holding the recording mediumsteady for an image reproduction interval; generating an image beam inthe optical assembly which projects a small part of the master elementon the recording medium; scanning the generated image beam along therecording medium for a selected distance in a first direction; repeatingthe scanning in the first direction after shifting the recording mediumin a second direction lateral to the first; and advancing the recordingmedium after a substantially complete raster image of the master elementhas been formed. 47) The method of creating at a format plane the imageof a master object comprising the steps of: momentarily holding arecording element stationary at a format plane in a given planarposition; projecting, with an optical transfer assembly of chosenmagnification, an image of an incremental part of the master object ontothe format plane; scanning the master object from one end to the otheralong a first direction by moving the optical transfer assembly;reciprocating the optical transfer assembly back to the first end aftershifting the planar position of the recording element perpendicularlyrelative to the first direction, and repeating the scanning steps untila complete image of the master object is formed on the recordingelement.